1. Field of the Invention
The present invention relates to an electronic device including an oxide film, a manufacturing method of the electronic device, and a sputtering target used for manufacturing the oxide film.
Note that an electronic device in this specification refers to any device that utilizes electric properties, and a semiconductor device that can function by utilizing semiconductor characteristics is included in the category of the electronic device. In addition, a device that utilizes electric properties (e.g., a capacitor, a coil, or a variety of electronic tubes), even when the device does not utilize semiconductor characteristics, is included in the category of the electronic device. Therefore, an electro-optical device, a semiconductor circuit, and an electronic appliance are all included in the electronic device.
2. Description of the Related Art
Oxides include oxides having a variety of properties, such as a conductive oxide, a semi-conductive oxide, and an insulating oxide and are used for a variety of applications in accordance with their properties. For example, silicon oxide is a typical insulating oxide and is broadly used for the purpose of element isolation, insulation between wirings, or the like in particular in an integrated circuit. In addition, tantalum oxide, barium titanate, or the like is used as a capacitor dielectric by utilizing an insulating property and a high dielectric constant.
As a conductive oxide, indium oxide (or indium oxide to which tin or the like is added) can be given. It is used as a material for a transparent conductive film utilizing an appropriate conductivity and a high transparent property of visible light. Besides, an yttrium barium copper oxide, a bismuth lead strontium copper oxide, or the like is known as a material having superconductor properties at a temperature of higher than or equal to the boiling point of nitrogen.
Some oxides have semiconductor characteristics. Examples of such oxides having semiconductor characteristics (semi-conductive oxides) are a tungsten oxide, a tin oxide, and an indium-gallium-zinc-based oxide (In—Ga—Zn-based oxide), and a thin film transistor in which such a semi-conductive oxide is used for a channel formation region is known (see Patent Documents 1 and 2). Further, in particular, properties of an In—Ga—Zn-based oxide also have been researched (Non-Patent Document 1).